We shall now briefly present a few techniques of the prior art along with their respective drawbacks.
1) Vertical Handover Using a Distributed Approach
A first prior art technique is described in Tobias Hosfeld et al.    “Supporting Vertical Handover by Using a Pastry Peer-to-Peer Overlay Network”, University of Würtzburg—Technical Report number 367, September 2005.
In this approach, the radio measurements (power of the received signal, block error rate etc) are distributed dynamically between the attachment points situated in a same decision zone. On the basis of these measurements, an access point deduces the radio conditions of its neighbors but only for the same technology as itself. To obtain measurements pertaining to the other technologies, links between the access points are set up by hand. The handover decision is always taken either by the terminal or by the current attachment point.
In this approach, there are no dynamic decision graphs, and only some decision parameters are dynamically distributed. This therefore cannot be used to adapt the decision to the applications and to the terminals.
2) Management of Multi-Access Radio Resources (GRRM)
A second prior art technique is described in: P. Magnussen, J. Lundsjo, J. Sachs and P. Wallentin, “Radio Resource Management Distribution in a Beyond 3G Multi-Radio Architecture”, IEEE GLOBECOM'04.
This approach proposes to centralize certain GRRM functions, such as load sharing, and to distribute other functions such as handover. The mobile terminal can form part of the distribution. In both cases, a specific node takes responsibility for a set of cells of a same technology. Thus, in the centralized approach, a multi-techno central node co-ordinates several mono-techno nodes which may be based on different technologies.
In this approach, a sort of decision graph is built but it is identical for all the applications and all the terminals under the co-ordination of a neighbouring management node. The same problem is found as in the case of the first known technique.
3) HMIP (Hierarchical Mobile IP) and NC-HMIP (Network Controlled Hierarchical Mobile IP)
A third prior art technique is described in the following documents:    H. Soliman et al., “Hierarchical Mobile IPv6 Mobility Management (HMIPv6)”, IETF RFC 4140; and    K. Guillouard et al., “Network-controlled Mobility within Radio Access Networks Based one WLAN Technologies”, Annales des Télécommunications, 3, 58, March 2003.
These two approaches enable the dynamic construction of a handover execution graph. A handover execution graph is represented by the set of entities taking part in the execution of the handover. In the proposed approaches, this execution is done at the IP level by extension of the Mobile IPv6 protocol. The handover execution graph is formed by entities such as: mobile terminal, access point, mobile anchorage point (MAP) and home agent (which is the special node responsible for tracking the position of the mobile terminal during its movements).
In this third prior art technique, there is no decision graph but a handover execution graph (see the definitions of these two types of graph here above). Furthermore, the built network is common to all the applications and to all the terminals under coverage of a same access router). Nor is there any dialogue between the different entities of the network for the building of this graph. Either it is the terminal alone that decides on the decision graph (HMIPv6) or it is a centralized node of the network (NC-HMIPv6). Thus, the same drawback is found as in the case of the first and second known techniques.